Long-lasting potentiation and depression without presynaptic activity

Abstract

1. Long-term potentiation (LTP) and long-term depression (LTD) require a rise in intracellular Ca2+ concentration ([Ca2+]i) in the postsynaptic CA1 pyramidal neuron to activate Ca-dependent biochemical processes. This rise in [Ca2+]i is a necessary trigger for the induction of LTP and LTD, but it is unclear if concurrent presynaptic activity is required for their induction or expression. 2. We used photolysis of the caged-Ca2+ compound nitr-5 to elevate postsynaptic [Ca2+]i. Long-lasting potentiation (LLP) and long-lasting depression (LLD) were obtained in the absence of presynaptic activity. 3. Because LLP and LLD share common features with LTP and LTD induced by presynaptic stimulation these results show that a rise in [Ca2+]i in the postsynaptic CA1 pyramidal neurons is necessary and sufficient for the induction and expression of LTP and LTD, and that concurrent presynaptic activity is not required.